Visual and chemical cues used in host location and acceptance by a dipteran parasitoid

Locating potential hosts for egg laying is a critical challenge in the life history of many insects. Female insects in several orders have evolved mec hanisms to find hosts by using olfactory and visual signals derived from th eir hosts. We describe visual and chemical cues used by the dipteran parasi toid Apocephalus paraponerae (Diptera: Phoridae) in the location and accept ance of its host ant Paraponera clavata (Hymenoptera: Formicidae: Ponerinae ). Our results show that A. paraponerae uses the visual cue of ant body siz e when locating hosts at short range and that these flies lay more eggs in ants that retain their surface chemicals than in ants with these chemicals removed. We compare the cues used by A. paraponerae with cues used by tephr itid fruit flies in location and acceptance of their hosts, and we suggest further avenues for the study of host location, acceptance, and host discri mination of A. paraponerae and other parasitoids of ants.